Closure for a filler neck having a seal

ABSTRACT

A closure stopper having a seal for a filler neck has first locking faces and a first sealing face, and the closure stopper has second locking faces and a second sealing face. The functions of the sealing ring and of the locking device are not impaired by the effects of temperature because (a) the smallest radius of the first sealing face is larger than the largest radius of the second sealing face, and (b) the sealing ring is a resilient circular ring with a first and a second sealing surface, of which, when the closure stopper is inserted, one surface bears against the first sealing face and the other face bears against the second sealing face. The sealing ring has a core made of resilient steel.

BACKGROUND OF THE INVENTION

[0001] The invention relates to a closure stopper having a seal for a filler neck. The filler neck has first locking faces and a first sealing face, and the closure stopper has second locking faces and a second sealing face, the sealing ring being arranged between the first and the second sealing face. The locking takes place by rotation of the closure stopper. This can be the closure of a fuel tank, of a cooling system or of a brake system. In all cases of use, a tight closure—locking—which can be checked has to be possible; in the first case of use, fuel vapors have additionally to be sealed off, for emission reasons.

[0002] The locking can take place in different ways, as a rule by rotation of the closure stopper. Threads, bayonet systems or hybrids thereof (for example, multiple threads with interruptions through which the mating element is threaded into the thread) are customary for this. Accordingly, the locking faces are generally spiral faces having a constant or variable pitch and a particular profile as ruling element. Both the closure stopper and the filler neck have mutually facing sealing faces with the seal seated in between. In all cases, a certain flexibility of the seal is required for reliable closure; in the case of threads, in order to achieve a sufficient closing pressure; in the case of bayonet systems, in order to permit a slight expansion of the seal again after exceeding a dead center; in the case of hybrid systems, in order to achieve the thread turns originating from the interruptions.

[0003] U.S. Pat. No. 4,133,346, DE 195 01 797 A1 and EP 874 762 B1 disclose such closure stoppers having a seal. In the first case, they are a normal O-ring made of plastic, in both the following two cases, they are shaped sealing rings made of plastic, which are U-shaped in cross section and whose limbs bear in each case against a sealing face. During closing, their limbs are moved toward each other and the profile is folded. As a result, the “spring deflection” of the shaped sealing ring is enlarged during closing.

[0004] All of these seals have the disadvantage that their elasticity is temperature-dependent to a great extent. However, the temperature range required for the functioning capability in vehicles reaches downward to minus 40 degrees. At these temperatures, plastic seals are virtually rigid and, as a result, are not only severely impaired in their sealing function, but also, for lack of deformability, obstruct the closing. This occurs least in the case of thread systems, but the latter are disadvantageous and are to be avoided because of their large and temperature-dependent free-running paths and the ratchets which are generally required in order to restrict the actuating force. This characteristic of the sealing rings means that bayonet systems and hybrids thereof are virtually unusable.

[0005] Added to this is also the fact that, for safety reasons, monitoring of the closed state by means of a positionally fixed sensor and a permanent magnet in the closure stopper is to be possible. In the case of thread systems, however, their indefinite and temperature-dependent angular position in the closed final state means that only the height position of the closure stopper or its insertion depth can be sensed, which requires a ring magnet of large diameter and is in no way sufficient for reliably checking whether it has actually been screwed in tightly.

[0006] The object of the invention, therefore, is to design the entire closure in such a manner that the functions of the sealing ring and of the locking device are not impaired by temperature effects.

SUMMARY OF THE INVENTION

[0007] According to the invention, the foregoing object is achieved by providing a closure stopper having a seal for a filler neck which has first locking faces and a first sealing face, and which closure stopper has second locking faces and a second sealing face, a sealing ring being arranged between the first and the second sealing face, wherein the largest radius of the first sealing face is smaller than the smallest radius of the second sealing face or the smallest radius of the first sealing face is larger than the largest radius of the second sealing face, the sealing ring is a resilient circular ring having a first and a second sealing surface, of which, when the closure stopper is inserted, one surface bears against the first sealing face and the other face bears against the second sealing face. In this case, it does not matter whether the largest radius of the first sealing face is smaller than the smallest radius of the second sealing face, or whether the smallest radius of the first sealing face is larger than the largest radius of the second sealing face; the main thing is for the two sealing faces to be situated at different radial distances from the axis of rotation of the closure stopper. The first relationship is better suited for a locking device (for example thread) on the outer circumference of the filler neck; the second for a locking device on the inner circumference of the filler neck.

[0008] By means of the different radial distances of the two sealing faces, the sealing ring is loaded and deformed transversely to the area of its extent, in the manner of a cup spring. In this loading case, the material utilization is very good, with the result that the sealing ring requires only a little structural space even at a high press-on force. However, the sealing ring does not have to be a planar or slightly conical, resilient circular ring, such as a cup spring; profiles which differ can also be realized. Above all, however, the spring constant of a planar or virtually planar circular ring consisting, in particular, of a metal is largely independent of the temperature. Therefore, at extremely low temperatures, the press-on pressure of the seal and the locking function are not impaired: the final position when using a thread is largely constant, the dead center of a bayonet can be resiliently overcome, and—in the case of a hybrid closure—the threading in at the interruption of the thread turns is possible. As a result, finally the thread may also be replaced by one of the two more practical closure systems (bayonet or hybrid).

[0009] In order to obtain readily sealing surfaces which bear tightly against the sealing faces when the closure stopper is inserted, various measures are possible. In one preferred embodiment, the sealing ring comprises a preferably planar, metallic core and a covering made of an elastomer which forms the sealing surfaces. Since the covering is entirely supported by the core, it can consist of a very soft elastomer which still yields somewhat even at very low temperatures.

[0010] In a feature of the invention, the sealing surfaces have thickened areas on the radii corresponding to their associated sealing faces. These thickened areas then form annular cushions which bear softly against the sealing faces at a higher, local press-on pressure.

[0011] In a further feature of the invention, one of the sealing faces is adjoined by a conical stop face which lies opposite the other sealing face. The deformation of the sealing ring is therefore restricted, with the result that the latter is not damaged even when rough force is applied.

[0012] In accordance with the invention, a particularly simple and reliable checking of the closed state is also possible. For this purpose, a single sensor is fitted on the filler neck and a magnet is fitted at a point on the circumference of the closure stopper. In addition, the final position of the closure stopper lies in such a narrow angular range that the sensor can respond to this angular position and it can thereby be reliably checked whether the closure stopper has actually been closed tightly. A magnet which is attached at one point on the circumference of the closure stopper and extends only over an angular range of 30 to 60 degrees is sufficient for this purpose. It can therefore also be substantially smaller and less expensive than an encircling ring magnet in the entire stopper. The invention therefore constitutes substantial, progress in the direction toward the “emission-free motor vehicle”.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The invention will be described and explained below with reference to figures, in which:

[0014]FIG. 1 shows a longitudinal section through the closure according to the invention,

[0015]FIG. 2 shows a cross section according to CC in FIG. 1,

[0016]FIG. 3 shows detail E in FIG. 1 in one embodiment,

[0017]FIG. 4 shows detail F in FIG. 3, further enlarged,

[0018]FIG. 5 shows detail F in FIG. 3, further enlarged, in a design variant,

[0019]FIG. 6 shows a plan view according to V in FIG. 1.

DETAILED DESCRIPTION

[0020]FIGS. 1, 2 and 3, a filler neck of a fuel tank, of a radiator or of a brake fluid container is denoted in summary by 1. It has here an internal thread 2, the thread turns of which are one possible embodiment of the first locking faces. An outer wall 3 joins the threaded part 2 via a flange. The flange forms a first sealing face 4. Furthermore, a further sensor 5 can be fastened to the filler neck 1 by means of binding 6.

[0021] In the exemplary embodiment shown, the locking faces are the spiral faces of a thread. However, they could likewise be the ramps of a bayonet or the thread turns of a hybrid closure, which turns extend only over part of the circumference. In any case, the closing takes place by rotation about an axis 7.

[0022] The closure stopper fitting into the filler neck 1 is denoted in summary by 10. It comprises a closure body 11, the outer thread 12 of which here forms the second locking faces which interact with the first locking faces 2, and which closure body furthermore forms second sealing faces 13. A sealing ring 15, which has yet to be referred to, is seated between second sealing faces 13 and first sealing faces 4. Furthermore, the closure stopper 10 has a gripping element 16 which is rotatingly connected via a ratchet 17 to the closure body 11 and forms an apron 18 protecting the seal. A magnet 20, whose approach is detected by the sensor 5, is fastened at one point on the lower edge of the closure body 11, approximately level with the sensor 5 in the closed state. The magnet needs only to take up a small angular range of 60 degrees maximum. If the magnet is positioned in such a manner that it comes to be situated in the vicinity of the sensor 5 in the correct closing state, the sensor signal states that the filler neck has been properly and tightly closed.

[0023] The sealing ring 15 is seated between the first sealing face 4 of the filler neck 1 and the second sealing face 13 of the closure stopper 10. In this case, it is essential that the largest radius 30 of the second sealing face 13 is smaller than the smallest radius 31 of the first sealing face 14. This is because as the two sealing faces 4, 13 approach each other, the sealing ring 15 is deformed in the manner of a cup spring. The sealing ring 15 is formed in a particularly simple manner if it is of planar design or of slightly conical design as a cup spring.

[0024] It can be seen in FIG. 4 that the sealing ring 15 has a core 35 made of a resilient material, preferably spring steel, which is surrounded by a plastic covering 36. The plastic covering 36 forms a first sealing surface 37 and a second sealing surface 38, of which the first interacts with the first sealing face 4 and the second with the second sealing face 13. In the great enlargement of FIG. 4, it can be seen that in the embodiment shown there, the second sealing face 13 is planar or slightly conical, and that on the latter, around the circle 39, an edge is formed which is adjoined by a conical or oppositely conical stop face 40. It restricts the deformation of the sealing ring 15 in the case of a forcible connection.

[0025]FIG. 5 shows a variant of the embodiment shown in FIGS. 1 to 4. This differs from the preceding ones firstly in the design of the sealing ring 45. Its first surface 46 and/or second surface 47 has/have a respective thickened area 48 or 49 which interacts with the corresponding sealing face 4 or 13. The thickened area improves the bearing and the local press-on pressure without surrendering the advantage of the planar or slightly conical core.

[0026] It is furthermore indicated in FIG. 5 that the closure stopper according to the invention and the associated filler neck can also have the locking faces the other way around. This means, for example, that the filler neck 1 has an external thread instead of the internal thread 2, and that the closure stopper 10 has an internal thread instead of the external thread. This is expressed in FIG. 5 by the fact that, as an alternative to the axis of rotation 7, an axis of rotation 50 is drawn in on the other side and again the largest radius 51 of the first sealing face 4 and the smallest radius 52 of the second sealing face 13 are plotted in the other direction.

[0027]FIG. 6 finally reveals the functional advantages of the solution according to the invention. The angular region denoted by 60 is the tolerance range of the magnet 20, the angular region denoted by 61 is the rotational angle range of the stopper. It can be seen that the latter range always lies within the tolerance range of the magnet and therefore always and reliably indicates that the closure stopper has been properly closed, or that it has not, depending in each case on the connection. Owing to the invention, there is no longer a noticeable temperature effect. 

1. A closure stopper having a seal for a filler neck which has first locking faces and a first sealing face, and which closure stopper has second locking faces and a second sealing face, a sealing ring being arranged between the first and the second sealing face, wherein a) the largest radius of the first sealing face is smaller than the smallest radius of the second sealing face or the smallest radius of the first sealing face is larger than the largest radius of the second sealing face, b) the sealing ring is a resilient circular ring having a first and a second sealing surface, of which, when the closure stopper is inserted, one surface bears against the first sealing face and the other face bears against the second sealing face.
 2. The closure stopper as claimed in claim 1, wherein the sealing ring comprises a metallic core and a covering made of an elastomer which forms the sealing surfaces.
 3. The closure stopper as claimed in claim 2, wherein the metallic core is an essentially planar spring ring.
 4. The closure stopper as claimed in claim 1, wherein the sealing surfaces have thickened areas at least on one of the radii corresponding to their associated sealing faces.
 5. The closure stopper as claimed in claim 3, wherein one of the sealing faces is adjoined by a conical stop face which lies opposite the other sealing face.
 6. The closure stopper as claimed in claim 1, wherein a single sensor is fitted on the filler neck and a magnet is fitted at a point on the circumference of the closure stopper.
 7. The closure stopper as claimed in claim 6, wherein the magnet is a magnet segment which extends over an angular range of 30 to 60 degrees. 